Rackets such as tennis, racquetball, squash, etc. are typically strung by hand using a stringing machine. The stringing machine assists in holding the racket frame, holding the string in place as it is positioned in the racket and applying the desired tension to the string. The invention relates to the stringing of racket frames and particularly to a product that assists with lacing/weaving of the cross-strings in such a frame. In the process of stringing rackets such as tennis rackets or squash rackets, it is the usual practice to clamp the racket frame onto a support which is rotatable on a vertical shaft and to first string the frame with the main strings which are parallel to the longitudinal axis of the handle. Once the main strings are properly tensioned and secured, the next step is to weave the cross-strings through the main strings. For lacing a cross-string, the string is inserted through a string hole located in the racket frame and is passed alternately under one main string and over the adjacent main string in the manner of a flat weave, whereupon the string is passed through the opposite string hole of the frame and is properly tensioned and temporarily secured by a string clamp. The next cross-string must be passed alternately under one main string and over the adjacent main string in the opposite manner as the previous cross-string in order for the string bed weave to be correct. Lacing the cross-strings by hand is a time-consuming operation which demands considerable time and manual dexterity and is often done erroneously. The two most common errors that occur during weaving the cross-strings are 1) a cross-string is pulled over or under more than 1 main string causing the string bed to be woven incorrectly or 2) a cross-string is woven in the exact same pattern as the previous cross-string causing the string bed to be woven incorrectly.
To facilitate the lacing of the cross-strings, there are four relevant apparatuses.                1) The first apparatus (U.S. Pat. No. 3,994,496—sports racket stringing aid) is a portable device for installing transverse strings in a sports racket having previously installed longitudinal (main) strings. One end can be hooked under existing strings for support while the bottom is held against alternate longitudinal (main) strings by pressure against a handle at the other end. Sliding of a member with undercut nitches holds the other alternate longitudinal (main) strings, to maintain transverse clearance for threading new cross-strings into place. This apparatus has the disadvantage that the hand-held apparatus applies pressure to the main strings in a way that can both damage the string surface as well as stretch the string causing a change in the string tension. Another disadvantage is that it is possible to improperly position the apparatus such that two consecutive cross-strings are placed in the exact same string alignment with respect to the main strings instead of alternating over and under the main strings.        2) The second apparatus (U.S. Pat. No. 4,452,452) is similar to the first. The apparatus of the invention comprises a first beam containing two rows of vertical slots with the slots of one row alternating with the slots of the other row to form pairs of slots, each comprising one slot from each row, the upper surface of said beam forming upper string support surfaces between these pairs of slots. The slots of each row have a spacing at least approximately corresponding to twice the average pitch of the main strings of the racket frame. The apparatus further comprises a second gripper beam adapted to be situated above said first beam, said second gripper beam vertically movable with respect to said first beam between open and closed positions, said second gripper beam having a plurality of downwardly facing string gripping surfaces, one associated with each slot of said first beam and, like said slots, arranged in pairs, the gripping surfaces of at least the majority of the gripping surface pairs being separated by a downwardly extending lug. By the provision of the two staggered rows of slots in the lower first beam and the corresponding gripping surfaces on the upper second gripper beam, it is now possible after lacing-in a cross-string to quickly change the channel between alternate main strings by shifting the apparatus in a lateral direction with respect to the main strings so as to move these strings from a first position in alignment with the slots of one row to a second position in alignment with the slots of the other row without the necessity of removing the apparatus from the cross-strings. This apparatus has the disadvantage that it is time consuming to use for the cross-stringing process. This apparatus also is a fixed length which does not easily accommodate rackets with different numbers of main strings (many tennis rackets have either 16 or 18 main strings). This known apparatus has the further disadvantage that when displacing the main strings to allow passage of the cross-strings this action is likely stretching the main strings which ultimately reduces the string tension.        3) The third apparatus (U.S. Pat. No. 7,862,455—Stringing Sandwich) is one that lays strings on top of each other within a frame; the overlying of the strings, once the process is finished, will create the arrays of intersections between the vertical and horizontal strings that create the net in a racket, such as a tennis racket, or squash racket. The apparatus has of a main section, a complementary overlap cover for the main section, a way of securing and undoing the main section to and from the frame of the racket, and an inlet and outlet passage for the strings to and from the main section. In addition, a preferred embodiment includes the main section with vertical and horizontal routes that overpass each other made of transparent plastic, and consisting of any number of vertical and horizontal routes. One disadvantage of the stringing sandwich is that sometimes the main section may not be a perfect fit to the design of the racket, since the design of the racket may not allow for that perfect fit, the fit between the geometric routes and the holes or openings on the frame of the racket. In other words, a perfect fit may not be 100% possible since some intersections are so close to the frame of the racket that the apparatus may need of the help the operator. The operator may be forced to input those intersections by hand, one by one, in those tight spots difficult to reach by the apparatus or Stringing Sandwich. Another significant disadvantage of the stringing sandwich is that when the apparatus is in place it prevents the tennis strings from being tensioned and held by a clamp until all strings are in place and the apparatus is removed. The typical method for stringing a racket is to tension and clamp each main string or cross-string as it is inserted through the racket frame.        4) The fourth apparatus (https://www.youtube.com/watch?v=6Tuc5ISysro) is in the public domain and is a length of twine tied in to connected loops and manually woven through the racket's main strings after they are in place. The twine is used to weave cross-strings by pulling the tennis string through the main strings. The primary disadvantage of this apparatus is that it can only be used to weave the cross-strings in one direction and then the operator has to manually weave the cross-strings in the opposite direction. Needing to alternate between two different insertion techniques for the cross-strings is both confusing and error-prone.        